Holdup prediction was attempted for the +45-degrees inclined data on the basis of the flow regimes present for approximately 60 correlations and theories. The B flow regime could not be predicted, as it generally gave a wide range of results of prediction because of the existence of a pressure loss reduction condition. In contrast to other geometries, the Wallis [51] relation was the single most successful method of prediction (handling the B + S, St + W, St + BTS, A + W, A + D, A + S. A + BTS, and B + Fro) and indicated that conditions at + 45-degrees geometry in many regards were very different from those for other geometries. Other successful prediction methods were the Nicklin [351 and Bonnecaze [7] models (S, A + S, B + Fro), the Rouhani correlations (B + S, D, S + Fro, A + BTS), and the Spedding-Chen models (B + S, S, F + D, A + W, A + D, A + S, A + BTS, B + Fro).